Emergency Stop Wiring for Multiple Remote ESTOPs


Thread Starter


Remote Emergency Stop Push button ES1, ES2...ES10 are wired by using separate 4 core cable from each ES to the MCC (motor control unit). Inside the MCC all those ESs are serially connected by putting jumper between the corresponding terminals.

This is commonly practice in the industry but I could not find a any international standard for this type of wiring.

1. Please help me to find the reference electrical or safety standard for the above mentioned system

2. Can the remote ES1 and ES2 serially connected at the ES1 push button without wiring towards MCC?

Since my client does not like the ASi Safe Estop system. Only they want is Hardwired Estop.

Bob Peterson

I doubt there is any international standards for such things. The main issue may well be that bringing all the wiring back to be point simplifies troubleshooting.
One thing to remember is if you are using 24 VDC E-Stop circuits, the length of cable becomes significant if you are wiring back to the MCC for each PB. Wire resistance can become enough to drop several volts from begining to end of a string. I did have one circuit wired in that manner where I had to add a 2nd E-Stop relay. I Broke the string into roughly equal parts to avoid the large voltage drop.

I like Bob's answer the best.

I have worked on conveyors over half mile in length with all pull cords in series. It's difficult to trouble shoot something like that/

We added a series of resistors that would short out in 100 Ohm increments using the normally open contacts indicating the first open switch, when that was reset it indicated the next and so forth.
> Since my client does not like the ASi Safe Estop system. Only they want is Hardwired Estop.

Try looking at ANSI / NFPA 79-*** Electrical Standard for Industrial Machinery or IEC 60204-1 Electrical equipment of machines; general requirements. If you are looking to monitor the E-Stops try searching Pretech Solutions Inc. at www.pretechsolutionsinc.com as they have solutions that monitor inputs the discerns between open and closed contact while monitoring for open, short and ground fault conditions.